Multi-glow switch tube



w. SIX ET AL 2,757,307

MULTI-GLOW SWITCH TUBE July 31, 1956 Filed June 29, 1955 fies/s 7744/66 Can-r50 4ux/4/4Ay 54 50 T2005 IN VEN TORS WILLEM SIX JACOBUS DOMBURG AGENT United States Patent MULTI-GLOW SWITCH TUBE Willem 'Six and Jacobus Domburg, Eindhoven, Netherlands, assignors to Hartford National Bank and Trust Company, Hartford, Conn., as trustee Application June 29, 1953, Serial No. 364,720 Claims priority, application Netherlands July 4, 1952 3 Claims. (Cl. 313-197) This invention relates to multi-glow switch tubes, that is to say discharge tubes comprising a rare-gas filling and electrodes consisting of crossed wires or rods, a number of glow discharge paths being formed at the crossings. Ten anode rods and ten cathode rods permit of obtaining a hundred discharge paths. Hence, the number of main electrodes is low relatively to the number of discharge paths.

The aforesaid tubes are inter alia employed in circuitarrangements for automatic telephone systems. In order to limit the number of auxiliary electrode throughputs the auxiliary electrodes for a number of discharge paths are combined to form a wire or rod extending substantially parallel with the associated main electrode.

The last-mentioned arrangement has a limitation in that, after striking one discharge path, the auxiliary electrode concerned assumes the potential of the discharge, so that in accordance with the distribution of the impedances over the anode circuit and the cathode circuit either the voltage of the auxiliary anode for the remaining discharge paths, of which it forms part, becomes so high or that of the auxiliary cathode becomes so low as to provoke spontaneous ignition, or the auxiliary electrode voltage has such a value as to bring about the discharge upon animpulse on a principal electrode, so that a main electrode was simultaneously connected to two circuits, which is undesirable.

The present invention has for its object to mitigate this limitation.

In a multi-glow switch tube, whose electrodes consist of crossed rods or wires and whose auxiliary electrodes extend parallel with the main electrodes, the auxiliary electrodes are provided with a resistance layer by which. the auxiliary current is limited to the desired value.

Said resistance layer assumes the potential of the discharge only where it is struck, whereas the remaining parts of the resistance layer retain substantially the same voltage as the source of voltage to which they are connected. In this manner a discharge is prevented from being struck in the discharge path not to be used.

In order that the invention may be readily carried into effect, it will now be described with reference to the accompanying drawing, given by way of example, of which Fig. 1 represents a section at right angles to the axis through a discharge tube according to the invention, and in which Fig. 2 is a vertical sectional view of such a tube.

Referring now to the drawing, the reference numeral 1 denotes a cylindrical glass wall of the tube, 2 denoting ice fiat mica discs provided with a big central hole. Between every two mica discs are provided narrow nickel rings 3 constituting the cathodes of the tube and obtained by curving plane rods in the form of a circle. The tube comprises ten cathodes. Ten elongated mica strips 4 enter by means of incisions into the mica discs 2. The elongated rods 5 constitute the anodes, the thinner rods 6 constituting the auxiliary anodes. The latter consists of an aluminium or zirconium wire which is oxidised at its surface. The parallel resistance of the total layer of an auxiliary anode is 0.025 to 0.05 megohm, hence the resistance in a discharge path is 0.25 to 0.5 megohm. Oxidation may be replaced by coating with a semi-conductor.

What is claimed is:

1. A multi-glow switch tube comprising an envelope, a rare-gas filling in said envelope, and an electrode system in said envelope; said system comprising a plurality of elongated cathode electrodes, a plurality of elongated main anode electrodes extending transverse to said cathode electrodes and defining therewith a plurality of main discharge paths, and an elongated auxiliary anode electrode extending substantially parallel to a main anode electrode and electrically associated with a plurality of said discharge paths, said auxiliary anode electrode controlling each of the discharge paths with which it is associated and drawing current in the process, said auxiliary electrode having a resistance surface layer throughout its length suflicient to limit the auxiliary current to a predetermined value, whereby the entire auxiliary electrode is prevented from assuming the potential of a particular discharge at a portion thereof.

2. A multi-glow switch tube comprising an envelope, a rare-gas filling in said envelope, and an electrode system in said envelope; said system comprising a plurality of ring-like cathode electrodes, a plurality of rod-like main anode electrodes extending transverse to said cathode electrodes and defining therewith a plurality of main discharge paths, and a rod-like auxiliary anode electrode extending substantially parallel to a main anode electrode and electrically associated with a plurality of said discharge paths, said auxiliary anode electrode consisting of a metal selected from the group consisting of aluminum and zirconium and controlling each of the discharge paths with which it is associated and drawing current in the process, said auxiliary electrode having an oxidized surface layer throughout its length exhibiting a resistance of between about 0.025 and 0.05 megohm, whereby the entire auxiliary electrode is prevented from assuming the potential of a particular discharge at a portion thereof.

3. A multi-glow switch tube as set forth in claim 1 wherein the resistance layer consists of a semi-conductor.

References Cited in the file of this patent UNITED STATES PATENTS 1,722,121 Wilson July 23, 1929 2,092,804 JObst Sept. 14, 1937 2,404,920 Overbeck July 30, 1946 2,417,730 Becker Mar. 18, 1947 2,419,485 Desch et al. Apr. 22, 1947 FOREIGN PATENTS 466,334 Canada July 4, 1950 

